1. Field of the Invention
The present invention relates to systems and methods for control of communication networks. More particularly, the present invention relates to systems and methods for data driven control of communication equipment.
2. Description of Related Art
In its simplest form, data communication takes place between two devices that are directly connected by some form of point-to-point transmission medium. However, in certain instances it is impractical for two devices or components to be directly, point-to-point connected. An example of such an instance is when there are a set of devices, each of which may require a link to many of the others at various times. This problem has been heretofore addressed by attaching multiple devices to a communication network. Each device, or station, is attached to a network node. The set of nodes to which stations attach is the boundary of a communication network that is capable of transferring data between two or more stations.
Communication networks may be categorized based on the architecture and the techniques used to transfer data. Two major different types of communication networks are switched networks and broadcast networks. Switched networks involve transfer of data from a source to a destination through a series of intermediate nodes that provide a switching facility to move the data from node to node. Broadcast networks involve no intermediate switching nodes; each station has a transmitter/receiver that allows communication over a common medium, so that a transmission from any one station is broadcast to and received by all other stations in the network.
As communication devices have become more complex, entities in different systems have developed the need to communicate. In a broad sense, entities include application programs, electronic mail facilities, voice telephones, and the like. Also in a broad sense, systems include computers, terminals, and the like. That is, in general, an entity may be defined to be anything capable of sending or receiving information, and a system defined to be a physically distinct object that contains one or more entities.
For two entities within a system to communicate successfully, they must speak the same language. That is, what is communicated, how it is communicated, and when it is communicated must conform to some mutually acceptable set of conventions between the entities involved. The set of conventions is referred to as a protocol, which may be defined as a set of rules governing the format and relative timing of message exchange between two entities. Functions performed by a conventional protocol include segmentation and reassembly, encapsulation, connection control, flow control, error control, synchronization, sequencing, addressing, multiplexing and transmission services, all of which functions are familiar to those skilled in the art. Protocols generally involve trade-offs of flexibility, versatility and efficiency. Compatibility is a desired attribute of protocols for practical reasons while modularity facilitates improving products.
Another concept that should be considered as background to the present invention is the concept of the network interface. The network interface is an interface towards a network, capable of connecting entities in separate systems that are not part of the network. Such entities access the network via the network interface using network access protocols. X.25 is well known to those skilled in the art as a packet-switched network access protocol standard.
As a final level to consider as part of the background of the present invention, "internets" have developed as interconnected sets of networks. Each constituent network supports communication among a number of attached devices. In addition, networks are connected by devices that may be referred to generically as "internetwork gateways". Internetwork gateways provide a communication path so that data can be exchanged between networks. A bridge is a simplified gateway that has been developed for use with homogeneous local networks. X.75 is a standard for a protocol that provides vertical circuit service across multiple X.25 networks.
A shortcoming and deficiency of the prior art that is addressed by the present invention is the lack of a system control protocol that simply but effectively coordinates subsystem protocols associated with entities within the system. That is, the prior art has heretofore lacked a system control protocol flexible enough to allow easy connection of new entities within the system and to allow easy modification (e.g., updating and enhancing) of protocols associated with such entities. Such a function is becoming more important with the advent of multi-service environments, such as the Integrated Services Digital Network ("ISDN"), and the Broadband Integrated Services Digital Network ("BISDN").